In situations where multiple logical networks share a common communication medium or channel, the networks compete for access to the channel, (i.e., they compete for bandwidth). In the absence of any coordination between the networks, they can destructively interfere with one another, reducing capacity utilization and the bandwidth (BW) available to stations within any network.
The scenario described above may arise when neighboring homes in residential neighborhoods or apartments deploy local area networks using a common medium within their individual dwellings. Often the networks share a channel, as is the case in wireless and in powerline networks. This scenario requires a method to allow the multiple networks to coordinate sharing the communication medium with one another.
This coordination problem is currently addressed by many methods. In some cases, contention access protocols, such as CSMA and its derivatives, are employed by all stations in the multiple networks sharing the medium. Contention access protocols, however, have been shown to be inefficient in providing QoS guarantees to AV and streaming applications which are increasingly popular.
In other cases, a central controller arbitrates among the multiple networks in deciding how the total available BW is apportioned. This centralized decision making scheme can cause large delays and incur heavy messaging overhead as the number of neighboring networks grows.
In some other cases, a distributed approach is used where each network coordinates and shares the available BW with its immediate neighboring networks only. There is no central authority that arbitrates among network devices. There is no chaining effect where a network has to coordinate with networks multiple hops away. This distributed method allows neighbor networks to have contention-free access of the channel and therefore improves capacity over contention access protocols.
No single method alone can solve the coordination problem efficiently under all network scenarios. Further, each method has limitations, which may not be acceptable. For example, any coordination method involving explicit message exchanges between Controllers in networks creates security issues.